Two Frogs and The Well

During a long, hot summer, the pond where two frogs lived dried up. When the rain failed to come, the frogs left their home in search of water. Sometime later they passed a deep well. On seeing the water below, one frog said, "Why not make this our new home? Look at all the water down there!"
The second frog responded and the first frog immediately felt foolish for suggesting such a thing. What'd the second frog say?